What is Sourdough Bread?

Niki Foster
Niki Foster

Sourdough bread is unique because it does not require any store-bought yeast, as do other rising breads. It features a symbiotic yeast and bacteria culture that arises naturally from microorganisms present in flour. A starter culture can be added, especially to produce a specific flavor, such as that associated with the Candida milleri yeast and the Lactobacillus sanfranciscensis bacteria of San Francisco sourdough bread, but it is not necessary. All one needs to make a sourdough culture is flour and water.

Sourdough bread is a popular, slightly sour-tasting bread.
Sourdough bread is a popular, slightly sour-tasting bread.

The bacteria in a sourdough bread culture is Lactobacillus, or lactic acid bacteria, which is also used in such foods as sauerkraut, kimchi, pickles, cheese, and yogurt. It is this bacteria that gives this bread its characteristic sour flavor, while the yeast allows the bread to rise. The yeast and bacteria naturally present in flour are activated by mixing in water and leaving it in a warm environment. Different types of flour are more or less rich in microorganisms, and sometimes unwashed organic grapes are added to the mixture to increase the natural yeast and help the culture to develop. Diastatic malt may also be added to a young culture to provide extra sugars for the yeast to feed on.

Sourdough bread has symbiotic yeast, but is unique because it doesn't require store-bought yeast.
Sourdough bread has symbiotic yeast, but is unique because it doesn't require store-bought yeast.

A sourdough culture, also known as a starter or sponge, must be "fed" daily when it is young with fresh flour and water. As the culture matures, it can be refrigerated and fed less often. A part of the culture is used for every new loaf of sourdough bread. A well maintained sourdough culture can serve a baker for many years.

Sourdough is one of the oldest types of bread. The 100% rye bread common in Northern Europe is one example of sourdough bread, and baguettes and other Southern European breads were traditionally made with sourdough before the advent of faster-growing yeast cultures. In the United States, sourdough bread from San Francisco is particularly famous. Some San Francisco sourdough cultures have been in use for 150 years. The sweet Amish Friendship Bread traditionally passed on to friends is another American sourdough bread example.

Sourdough starter is fed daily with yeast and water.
Sourdough starter is fed daily with yeast and water.
Niki Foster
Niki Foster

In addition to her role as a wiseGEEK editor, Niki enjoys educating herself about interesting and unusual topics in order to get ideas for her own articles. She is a graduate of UCLA, where she majored in Linguistics and Anthropology.

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make pancakes with the left over starter, if you don't want to feed it each day. Just use the starter and add eggs, salt, sugar, etc., and it will make fantastic pancakes. Look online for a recipe! YUM! Then, if you don't eat all of them, freeze the leftovers for another day.


I always wondered what gave sourdough it's classic "sour" taste -- I had some vague notion that it had to do with a sourdough starter bread, but I never really knew.

I'm curious, though, now does the fermented starter impact the sourdough bread's nutrition value? Is it one of those things like yogurt, where the fermentation process adds nutritional value, or is it just done for the taste?

As you can tell, I'm not much of a baker, but I do love to eat baked goods, so I like to learn as much about the baking process as I can. And, out of curiosity, who started the whole making sourdough bread without yeast thing? I mean, somebody had to make it the first time, so I wonder how they got the idea to make bread with a starter, rather than yeast.

Inquiring minds...


I love eating sourdough bread, but frankly, making it sounds like a total pain. I'm not that much of a baker anyway, so I'm not the best person to make comments, but still, having to "feed" something that you make is enough to turn me off of baking sourdough bread.

Now, if I could find a sourdough bread recipe with yeast, like normal bread recipes, I would consider it, since that sounds at least marginally easier.

But then, maybe I just don't have the right baking attitude -- frankly, the whole thing just seems to take way too long, and the results last for such a short time that I'd much rather just pick up a nice artisan loaf from the store than go through all the trouble of making it myself.


Sourdough bread is great, but it can be a pain to deal with all the extra sourdough bread starter that you get, especially if you're making something like Amish friendship bread.

And the worst part is, it's not like you want to just throw away all the extra starter, since you went through the trouble of making it and feeding it to begin with.

I usually end up freezing mine in ziploc bags until I find someone that I can give it to, or until my husband gets fed up with all the bags clogging up the freezer and throws them away.

If anybody has some tips on what to do with leftover starter, I'd love to hear them -- I do hate throwing all that starter away, but I just love baking sourdough bread too much to stop!

Thanks all!

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